The present invention is generally related to purge control devices, and, more particularly, to a unibody electromagnetic valve for controlling the flow of fuel vapors. The invention is further related to valve-constructing techniques that enable to produce a valve with low acoustic noise and reduced permeability relative to the fuel vapors passing through the valve.
Environmental regulations for automotive-related emissions have been evolving over the years to more rigorously prescribe the levels of emissions that may be discharged into the atmosphere, such as fuel vapors that may accumulate in the fuel tank of an automobile. Accordingly, evaporative systems for reducing the discharge of these vapors into the atmosphere have to accurately meet such regulations. At the same time, the evaporative systems should be reliably and affordably constructed to enable suppliers in the automotive industry to successfully compete in the marketplace.
Known purge control devices generally use an assembly of many discrete parts, which incrementally add to the cost and weight of the device and tend to adversely impact the overall reliability of the device. FIG. 1 illustrates one known purge control device 10 including a solenoid valve 12 having a relatively heavy plunger 14. The valve may operate using pulse width modulation (PWM) techniques at a preset frequency, such as 16 Hz. Although the valve provides appropriate flow control to the fuel vapors that pass therethrough, this type of valve may generate objectionable levels of acoustic noise during its operation. Most customers view low noise as a desirable feature in automotive applications, and, consequently, the ability to provide a valve that in operation has low levels of acoustic noise is a very desirable feature for suppliers of automotive components, such as the assignee of the present invention.
The body of a valve, such as that illustrated in FIG. 1, is generally made from plastic, and it is known that there might be some diffusion of fuel vapors through the body of the valve. The level of this diffusion is relatively low and this has not been an issue in view of present environmental regulations. However, it is anticipated that there may be requirements that may be enacted in the future that would mandate eliminating or substantially reducing the levels of such a diffusion.
In view of the foregoing considerations, it would be desirable to provide a valve, such as may be used in a purge control device, that in operation produces relatively low levels of acoustic noise. It would be further desirable to provide a valve made of materials with reduced permeability relative to the fuel vapors passing through the valve. It would be further desirable to provide a valve with fewer parts relative to the number of parts traditionally used in the industry so as to enable incremental cost and weight savings as well as improved reliability.
Generally, the present invention fulfills the foregoing needs by providing in one aspect thereof, a valve for a purge control device. The valve includes an integral body. The valve further includes a resilient member inserted into the integral body. The resilient member is electromagnetically responsive so that the member can be selectively actuated between respective open and close conditions. An electromagnetic actuator is affixed to the integral body to generate an electromagnetic field for selectively actuating the resilient member between the open and closed conditions. The mass of the resilient member is sufficiently low so that the level of noise produced by the valve is correspondingly low.
In another aspect thereof, the present invention further fulfills the foregoing needs by providing a method for constructing a valve for a purge control device. The method allows constructing an integral body. The method further allows inserting a resilient member into the integral body. The resilient member is electromagnetically responsive so that the member can be selectively actuated between respective open and close conditions. An electromagnetic actuator is coupled to the integral body to generate an electromagnetic field for selectively actuating the resilient member between the open and closed conditions. The mass of the resilient member is sufficiently low so that the level of noise produced by the valve is correspondingly low.